Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including volatile and non-volatile memory. Volatile memory can require power to maintain its data and includes random-access memory (RAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM), among others. Non-volatile memory can provide persistent data by retaining stored data when not powered and can include NAND flash memory, NOR flash memory, read only memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), phase change random access memory (PCRAM), resistive random access memory (RRAM), and magnetic random access memory (MRAM), such as spin torque transfer random access memory (STT RAM), among others.
Memory devices can be combined together to form a memory system such as a solid state drive (SSD). A solid state drive can include non-volatile memory (e.g., NAND flash memory and NOR flash memory), and/or can include volatile memory (e.g., DRAM and SRAM), among various other types of non-volatile and volatile memory. An SSD can be used to replace hard disk drives as the main storage device for a computer, as the solid state drive can have advantages over hard drives in terms of performance, size, weight, ruggedness, operating temperature range, and power consumption. For example, SSDs can have superior performance when compared to magnetic disk drives due to their lack of moving parts, which may avoid seek time, latency, and other electro-mechanical delays associated with magnetic disk drives. SSD manufacturers can use non-volatile flash memory to create flash SSDs that may not use an internal battery supply, thus allowing the drive to be more versatile and compact.
Memory systems can include a number of discrete memory devices (e.g., packages), which can be multi-chip packages (MCPs), and a memory system itself can be considered a memory device. A MCP can include a number of memory dies and/or chips each having a number of memory units associated therewith. The memory units can execute commands received from a host, report status to the host, and can include a number of memory arrays along with peripheral circuitry. The memory arrays can include memory cells that can be organized into a number of physical groups (e.g., blocks), with each of the groups capable of storing multiple pages of data.
In various memory systems, multiple memory devices are coupled to a controller via a shared bus. The controller can regulate performance of various operations such as erase operations, program operations, and read operations, for example. The interaction between the controller and the multiple memory devices can affect various characteristics of a memory system including power consumption, processing speed, and/or data integrity, among other memory system characteristics.